Left Turn
Overview
Left turn (Korean: 좌회전; Hanja: 左回轉) is both a maneuver in which a driver turns a vehicle to the left relative to the direction of travel and a traffic act whose method of passage is strictly prescribed under the Road Traffic Act by signals, signs, and road surface markings. Left turns at intersections have many conflict points with oncoming straight-through vehicles, pedestrians, and two-wheeled vehicles, and are classified as a representative dangerous maneuver with a high proportion of fatal injuries among all traffic accidents. Countries manage left turns with separate signal systems and lane designs, and South Korea operates unprotected left turns and protected left turns in parallel.
Main Content
Legal Definition and Basic Principles
Article 25 of the Road Traffic Act prescribes the method for left turns at intersections. A vehicle intending to turn left must slow down in advance along the center line of the road and turn using the inner side of the center of the intersection, and must not turn in advance along the left edge. At intersections with traffic lights, the signals must be followed, and where there is a left-turn signal (green arrow), that signal must be followed without exception. A left turn in violation of a signal is subject to fines and penalty points, and if an accident occurs, it may lead to criminal liability.
Types of Left Turns
- Protected left turn: A method of turning while a dedicated green arrow signal for left turns is on, completely separated from oncoming vehicles. It is the safest, but the signal cycle is long, increasing waiting time.
- Unprotected left turn: A method of turning without a separate left-turn signal, within the scope of not obstructing oncoming straight-through vehicles under a green light. It is possible only at intersections where an 'unprotected' sign is installed, and the right of way must be yielded to straight-through vehicles on the opposite side.
- Simultaneous-signal left turn: A method in which the straight-through signal and left turn are given together; conflicts with oncoming straight-through vehicles occur, so it is sometimes operated in combination with the unprotected method.
- Roundabout: A structure in which vehicles enter and exit by rotating counterclockwise instead of using the concept of a left turn, and it is expanding as a design that reduces left-turn accidents themselves.
Left-Turn Waiting and Lane Operation
Left-turn lanes are separated as dedicated lanes at the intersection approach, and left-turn stop lines and U-turn zones are often marked together. Actuated left-turn signals use vehicle detectors to grant a left-turn signal only when there are waiting vehicles, so as not to obstruct straight-through traffic. Left-turn prohibition zones are designated by solid yellow lines, time-specific prohibition signs, no-left-turn signs, and the like, and violations are subject to fines.
Left Turns and Accident Types
The representative types of left-turn accidents are collisions with oncoming straight-through vehicles, collisions with pedestrians on crosswalks, and side collisions with right-turning vehicles and two-wheeled vehicles. In particular, in unprotected left-turn sections, the driver's securing of visibility and judgment on yielding determine whether an accident occurs. Accidents during left turns tend to place a large degree of fault on the left-turning vehicle, and whether signals were observed and whether the vehicle slowed down become key issues in calculating the fault ratio.
Recent Trends
In 2024–2025, policies to expand unprotected left-turn sections and reduce signal waiting time are continuing, while AI-based signal optimization systems to reduce intersection accidents are being introduced in major cities. This is a method of automatically adjusting left-turn signal timing by reflecting real-time traffic volume through detectors and image analysis. In the autonomous vehicle field, unprotected left turns and pedestrian prediction are regarded as the most difficult judgment tasks, and algorithms that estimate the speed and intention of oncoming vehicles are being studied as core technologies. On major urban arterial roads, road designs that reduce left turns and induce 'right turn then U-turn (P-turn)' or roundabouts are increasing, and roundabouts are continuing to be expanded nationwide as of 2025. In addition, the issue of two-wheeled vehicles and bicycles encroaching on lanes while waiting to turn left and the strengthening of the pedestrian-first principle are being discussed together.
Related Topics
- [[도로교통법]]
- [[신호등]]
- [[회전교차로]]
- [[비보호좌회전]]
- [[교통사고]]
- [[자율주행차]]